Detection of Echinococcus multilocularis DNA in fox faeces using DNA amplification

Area of Science:

• Veterinary Parasitology
• Molecular Diagnostics
• Wildlife Epidemiology

Background:

• Echinococcus multilocularis is a significant tapeworm parasite with fox populations acting as definitive hosts.
• Accurate detection of E. multilocularis in fox faeces is crucial for epidemiological surveillance and public health.
• Existing diagnostic methods may lack the sensitivity required for early or low-level parasite detection.

Purpose of the Study:

• To develop and validate a novel DNA extraction method for preparing DNA from fox faeces suitable for Polymerase Chain Reaction (PCR) amplification.
• To establish a sensitive and specific PCR assay for the detection of Echinococcus multilocularis DNA.
• To compare the diagnostic sensitivity of the developed PCR method with traditional microscopical examination of fox faeces.

Main Methods:

• A novel DNA isolation procedure involving KOH lysis, phenol-chloroform extraction, and matrix-based purification (Prep-A-Gene) was employed.
• The U1 small nuclear RNA (snRNA) gene of E. multilocularis was targeted for PCR amplification.
• Sensitivity was assessed by spiking faeces with known amounts of E. multilocularis DNA or eggs, and specificity was tested against related tapeworm species.
• PCR products were confirmed using Southern blotting and hybridization with an oligonucleotide probe.

Main Results:

• The developed method successfully isolated E. multilocularis DNA from fox faeces, yielding consistent PCR amplification across 32 isolates.
• The assay demonstrated high specificity, with no amplification observed for DNA from other tapeworm species, including Echinococcus granulosus.
• The PCR method achieved a sensitivity of 1 E. multilocularis egg per 4 grams of faeces.
• In field samples, 7 out of 10 faecal samples from foxes without observed adult worms were PCR positive, indicating higher sensitivity than necropsy.
• 18 out of 19 faecal samples from foxes with adult worms were PCR positive.

Conclusions:

• The novel DNA preparation method combined with PCR provides a highly sensitive and specific tool for detecting Echinococcus multilocularis in fox faeces.
• This molecular approach significantly enhances diagnostic sensitivity compared to traditional microscopical examination, aiding epidemiological studies.
• The findings support the implementation of this PCR-based method for routine surveillance of Echinococcus multilocularis in wildlife populations.